Add i18n support across the catalog and map layers

[arte-dev]

What this PR does

• Query GeoServer using the user's selected language to load i18n layer info and legends.
• Translate translate#-prefixed strings found in the catalog JSON when rendering the catalog UI.
• Improve WMS language handling, attempting to serve languages by:
  A) the user's language, B) the fallback language, C) any other available.
• Add i18n support to the titles and descriptions of data catalog items shown in the right-hand preview panel.
• Translate catalog names in getPath using a reactive i18n instance.
• Improve handling of server exceptions, specifically ServiceExceptionReport, to surface the concrete error (e.g. when adding data from a URL with AcceptLanguages against a server that does not support i18n).
• Retry requests without the AcceptLanguages parameter when the server fails to serve a request that includes it.
• Fix invalid <p> nesting in FeedbackLinkCustomComponent: since FeedbackLink renders inside a markdown-generated <p>, calling parseCustomMarkdownToReact added another <p>. Use { inline: true } so md.renderInline emits only inline elements.

Checklist

• There are unit tests to verify my changes are correct or unit tests aren't applicable (if so, write quick reason why unit tests don't exist)
• I've updated relevant documentation in doc/.
• I've updated CHANGES.md with what I changed.
• I've provided instructions in the PR description on how to test this PR.

[CLAassistant]

All committers have signed the CLA.